Lubricating composition

ABSTRACT

There is disclosed a lubricant composition comprising a major amount of a base oil; and a minor amount of a synergistic additive composition comprising: (i) a triazole compound substituted with an aryl moiety, with the proviso that the triazole compound is not an alkyl bis-3-amino-1,2,4-triazole; and (ii) a nitrogen-containing compound represented by the formula: 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono.

REFERENCE TO RELATED APPLICATION

This application is a Continuation-In-Part and claims the benefit ofU.S. patent application Ser. No. 11/609,084, filed Dec. 11, 2006, thedisclosure of which is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure is directed to additive and lubricantcompositions and methods for use thereof. More particularly, thisinvention is directed to an additive composition comprising asynergistic combination comprising (i) a triazole compound, and (ii) anitrogen-containing compound.

BACKGROUND OF THE DISCLOSURE

Diesel engines are used in a variety of applications and lubricantcompositions for use in diesel engines are well known. Among the varioustypes of diesel engines are the medium speed diesel engines, which areused in applications where thousands of horsepower (e.g., 2000 to 10,000horsepower) are needed. This includes propulsion engines of deep-draft,sea-going vessels, workboats operating in the inland and coastalwaterways, and stationary or continuous electrical power generation formanifold applications including rail locomotives, offshore drillingplatforms, and industrial facilities and buildings. Typically, theseengines run at a speed of about 100 to about 1,200 rpm. This demandingenvironment results in oxidation of the oil, which can result incorrosion of the metals present in the engine.

Medium speed diesel engines are unique among diesel engines generallybecause these engines frequently have silver parts, such as silverbearings. Thus, apart from providing stability against oxidation andprotection against the formation of sludge and carbonaceous deposits,lubricating compositions intended for use in medium speed diesel enginesmust be formulated with specialized silver protecting agents in orderthat silver bearings in the engine are not attacked either by theadditives in the oil or by the decomposition products produced duringextended engine operation. Such agents, often referred to as silverlubricity agents, protect against extreme pressure, wear and corrosion.

A typical engine lubricating composition might comprise extreme pressureagents and antiwear agents. The most commonly used extreme pressure andantiwear agents are sulfur-containing compounds, such as zincdialkyldithiophosphates (ZDDP). However, it is well known that somesulfur-containing compounds cannot be used in engines having silverparts given their known propensity to damage the silver parts. Thisrecognized tendency is explained, for example, in U.S. Pat. No.4,428,850. Thus, it is desirable to find an additive composition thatcan provide oxidation protection and in some cases can be essentiallyfree of these potentially damaging compounds containing active sulfur.

SUMMARY OF THE DISCLOSURE

In accordance with the disclosure, there is provided an additivecomposition comprising (i) a triazole compound substituted with an arylmoiety, with the proviso that the triazole compound is not an alkylbis-3-amino-1,2,4-triazole; (ii) a nitrogen-containing compoundrepresented by the formula:

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono

In an aspect, there is provided a lubricant composition comprising amajor amount of a base oil; and a minor amount of a synergistic additivecomposition comprising (i) a triazole compound substituted with an arylmoiety, with the proviso that the triazole compound is not an alkylbis-3-amino-1,2,4-triazole; and (ii) a nitrogen-containing compoundrepresented by the formula:

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.

In another aspect, there is also provided a lubricant compositioncomprising an additive composition comprising (i) a triazole compoundsubstituted with an aryl moiety, with the proviso that the triazolecompound is not an alkyl bis-3-amino-1,2,4-triazole; and (ii) anitrogen-containing compound represented by the formula:

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.

Moreover, there is provided a method of improving oxidation protectionof a lubricant composition, said method comprising: providing to amachine a lubricant composition comprising a major amount of a base oil;and a minor amount of a additive composition comprising (i) a triazolecompound substituted with an aryl moiety, with the proviso that thetriazole compound is not an alkyl bis-3-amino-1,2,4-triazole; and (ii) anitrogen-containing compound represented by the formula:

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.

Further, there is provided a method for operating a machine comprisingadding a lubricating composition comprising a major amount of a baseoil; and a minor amount of an additive composition comprising (i) atriazole compound substituted with an aryl moiety, with the proviso thatthe triazole compound is not an alkyl bis-3-amino-1,2,4-triazole; and(ii) a nitrogen-containing compound represented by the formula:

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.

Additionally, there is provided a method of lubricating at least onemoving part of a machine, said method comprising contacting at least onemoving part with a lubricant composition comprising a major amount of abase oil and a minor amount of a synergistic additive compositioncomprising: (i) a triazole compound substituted with an aryl moiety,with the proviso that the triazole compound is not an alkylbis-3-amino-1,2,4-triazole; and (ii) a nitrogen-containing compoundrepresented by the formula:

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.

Additional objects and advantages of the disclosure will be set forth inpart in the description which follows, and/or can be learned by practiceof the disclosure. The objects and advantages of the disclosure will berealized and attained by means of the elements and combinationsparticularly pointed out in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure, as claimed.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure generally relates to a lubricant compositioncomprising a major amount of a base oil and a minor amount of anadditive composition comprising (i) a triazole compound substituted withan aryl moiety, with the proviso that the triazole compound is not analkyl bis-3-amino-1,2,4-triazole; and (ii) a nitrogen-containingcompound represented by the formula:

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono. As used herein, theterm “major amount” is understood to mean an amount greater than orequal to 50 wt. %, for example from about 80 to about 98 wt. % relativeto the total weight of the composition. Moreover, as used herein, theterm “minor amount” is understood to mean an amount less than 50 wt. %relative to the total weight of the composition.

As used herein, “aromatic” or “aryl”, unless expressly stated otherwise,refers to the typical substituted or unsubstituted non-aliphatichydrocarbyl or heterocyclic moieties of this class, e.g., apolyunsaturated, typically aromatic, hydrocarbyl cyclical, orheterocyclic, substituent, which can have a single ring or multiplerings (up to three rings) that are fused together or linked covalently.Typical hydrocarbyl aromatic moieties include phenyl, naphthyl,biphenylenyl, phenanthrenyl, phenalenyl, and the like. Such moieties areoptionally substituted with one or more hydrocarbyl substituents. Alsoincluded are aryl moieties substituted by other aryl moieties, such asbiphenyl. Heterocyclic aryl or aromatic moieties refers to unsaturatedcyclical moieties containing carbon atoms in the ring and additionallyone or more hetero atoms, which are typically oxygen, nitrogen, sulfurand/or phosphorus, such as pyridyl, thienyl, furyl, thiazolyl, pyranyl,pyrrolyl, pyrazolyl, imidazolyl, pyrazinyl, thiazolyl, etc. Suchmoieties are optionally substituted with one or more substituents suchas hydroxy, optionally substituted lower alkyl, optionally substitutedlower alkoxy, amino, amide, ester moieties and carbonyl moieties (e.g.,aldehyde or ketonic moieties).

As used herein, “alkaryl”, unless expressly stated otherwise, refers toan alkyl moiety substituted by the typical substituted or unsubstitutednon-aliphatic hydrocarbyl or heterocyclic moieties described above.Typical aryl moieties include phenyl, naphthyl, benzyl, and the like.Such moieties are optionally substituted with one or more substituentssuch as hydroxy, optionally substituted alkyl, optionally substitutedalkoxy, amino, amide, ester moieties and carbonyl moieties (e.g.,aldehyde or ketonic moieties).

As used herein, the terms “hydrocarbon”, “hydrocarbyl” or “hydrocarbonbased” mean that the moiety being described has predominantlyhydrocarbon character within the context of this invention. Theseinclude moieties that are purely hydrocarbon in nature, that is, theycontain only carbon and hydrogen. They can also include moietiescontaining substituents or atoms which do not alter the predominantlyhydrocarbon character of the moiety. Such substituents can includehalo-, alkoxy-, nitro-, etc. These moieties also can contain heteroatoms. Suitable hetero atoms will be apparent to those skilled in theart and include, for example, sulfur, nitrogen, oxygen, and phosphorus.Therefore, while remaining predominantly hydrocarbon in character withinthe context of this invention, these moieties can contain atoms otherthan carbon present in a chain or ring otherwise composed of carbonatoms.

As used herein, the term “synergy” and its grammatical variations referto the interaction of elements that, when combined, produce a totaleffect greater than the sum of the individual elements.

A triazole compound suitable for use in the compositions of the presentdisclosure can be any triazole substituted with an aryl moiety, with theexception of an alkyl bis-3-amino-1,2,4-triazole. In some embodimentsthe triazole compound is a 1,2,3-triazole compound. In other embodimentsthe triazole compound is a 1,2,4-triazole compound.

For example, the triazole compound can be substituted with a substitutedor unsubstituted aryl moiety comprising a single ring or multiple rings,for example covalently linked rings. Non-limiting examples ofsubstituted aryl moieties comprising covalently linked rings includebiphenyl, 1,1′-binaphthyl, p,p′-bitolyl, biphenylenyl, and the like. Asanother example, the aryl moiety can comprise multiple fused rings.Non-limiting examples of aryl moieties comprising multiple fused ringsinclude naphthyl, anthryl, pyrenyl, phenanthrenyl, phenalenyl, and thelike. As a further example, the aryl moiety can comprise a single ringcovalently linked to the triazole. Non-limiting examples of arylmoieties comprising a single ring covalently linked to the triazoleinclude phenyl and the like. As another example, the aryl moiety cancomprise a single ring fused to the triazole. A non-limiting example ofsuch a compound includes benzotriazole. An example of a commerciallyavailable triazole compound suitable for use herein is a benzotriazole,which is an off-white solid having a melting point ranging from 95-99°C., a flashpoint of 170° C., and a water solubility of 25 g/L at 20° C.The triazole compound can be combined/reacted/mixed with other additivesin order to increase its solubility in a composition.

In an embodiment, the triazole compound can be represented by formula(I) below:

wherein R³ is selected from the group consisting of hydrogen and atleast one alkyl moiety comprising from about 1 to about 24 carbon atoms,and wherein R⁴ is selected from the group consisting of hydrogen, atleast one alkyl moiety comprising from about 1 to about 24 carbon atoms,and a substituted hydrocarbyl moiety. In another embodiment, R³ and R⁴of the triazole compound represented by formula (I) can eachindependently comprise from about 1 to about 16 carbon atoms.

The triazole compound can be present in the lubricant and additivecompositions in any effective amount, which can be readily determined byone of ordinary skill in the art. Moreover, the triazole compound can bepresent in any synergistic effective amount. In an embodiment, thelubricating composition of the present disclosure can comprise fromabout 0.01 wt. % to about 10 wt. %, and for example from about 0.05 wt.% to about 0.5 wt. %, of the triazole compound, relative to the totalweight of the lubricating composition. In another embodiment, theadditive composition of the present disclosure can comprise from about0.01 wt. % to about 3 wt. % of the triazole compound, relative to thetotal weight of the additive composition.

The disclosed compositions can also comprise a nitrogen-containingcompound. There is no particular restriction on the type ofnitrogen-containing compound that can be used in the disclosedcompositions of the present disclosure. Generally, a nitrogen-containingcompound suitable for use herein can be represented by formula (II)below:

wherein R¹ and R² can each be independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono. For example, R¹ andR² of the nitrogen-containing compound can both comprise an aryl moietycomprising from about 6 to about 30 carbon atoms. Non-limiting examplesof aryl moieties include alkphenyl of phenyl, benzyl, naphthyl, andalkaryl. As another example, R¹ and R² can each independently comprisealkaryl, such as alkphenyl or alknaphthyl, wherein the alkyl moietycomprises from about 4 to about 30, and for example from about 4 toabout 12, carbon atoms. As still another example, R¹ and R² can eachindependently comprise a substituted or unsubstituted aryl moiety.Non-limiting examples of substituents for the aryl moiety can include analkyl moiety comprising from about 1 to about 20 carbon atoms, hydroxyl,carboxyl, and nitro moieties. As another example, R¹ and R² can eachindependently be an alkyl substituted benzyl, phenyl, or naphthyl.

Other non-limiting examples of nitrogen-containing compounds that aresuitable include: phenylamine; diphenylamine; triphenylamine; variousalkylated phenylamines, diphenylamines and triphenylamines;N,N′-bis(4-aminophenyl)-alkylamine; 3-hydroxydiphenylamine;N-phenyl-1,2-phenylenediamine; N-phenyl-1,4-phenylenediamine;dibutyldiphenylamine; dioctyldiphenylamine; dinonyldiphenylamine;phenyl-alpha-naphthylamine; phenyl-beta-naphtylamine;diheptyldiphenylamine; and p-oriented styrenated diphenylamine.Additional non-limiting examples of suitable nitrogen-containingcompounds and their methods of preparation include those in U.S. Pat.No. 6,218,576, which descriptions are incorporated herein by reference.

The nitrogen-containing compounds used herein can comprise a structureother than that shown above in formula (II) which shows but one nitrogenatom in the molecule. Thus, the nitrogen-containing compound cancomprise a different structure provided that at least one nitrogen hasat least one aryl moiety attached thereto, e.g., as in the case ofvarious diamines having a secondary nitrogen atom as well as an arylattached to one of the nitrogens.

The nitrogen-containing compounds used herein can have antioxidantproperties in the disclosed compositions when used alone but can alsodemonstrate synergistic properties in the presence of a triazolecompound described herein. For example, the oxidation protectionafforded by the triazole compound and/or the nitrogen-containingcompound alone can be significantly enhanced if these materials arepresent in the disclosed lubricant compositions, thereby demonstratingsynergism. The synergy can allow a lower treat rate of the additivecomposition needed to achieve a desired level of achieving oxidationprotection than would otherwise be required if either the triazolecompound or nitrogen-containing compound were to be used alone.Additionally, the nitrogen-containing compounds used herein should besoluble in a final lubricant composition.

The amount of the nitrogen-containing compound in the disclosedcompositions can vary depending upon specific requirements andapplications. In an aspect, the nitrogen-containing compound can bepresent in a synergistic effective amount. In an embodiment, thelubricating composition of the present disclosure can comprise fromabout 0.01 wt. % to about 10 wt. %, and for example from about 0.3 wt. %to about 3 wt. %, of the nitrogen-containing compound, relative to thetotal weight of the lubricating composition. In another embodiment, theadditive compositions of the present disclosure can comprise from about0.07 wt. % to about 33 wt. % of the nitrogen-containing compound,relative to the total weight of the additive composition.

The compositions disclosed herein can optionally contain additives, suchas dispersants, ash-containing detergents, ashless-detergents, overbaseddetergents, pour point depressing agents, viscosity index modifiers,ash-containing friction modifiers, ashless friction modifiers,nitrogen-containing friction modifiers, nitrogen-free frictionmodifiers, esterified friction modifiers, extreme pressure agents, rustinhibitors, antioxidants, corrosion inhibitors, anti-foam agents,titanium compounds, titanium complexes, organic soluble molybdenumcompounds, organic soluble molybdenum complexes, boron-containingcompounds, boron-containing complexes, tungsten-containing compounds,tungsten-containing complexes, and combinations thereof. In an aspect,the compositions can comprise various levels of at least onetitanium-containing compound depending on the needs and requirements ofthe application. In another aspect, the compositions can comprisevarious levels of at least one molybdenum-containing compound dependingon the needs and requirements of the application.

In an embodiment, the lubricant compositions of the present applicationcan be essentially free, such as devoid, of compounds containing freeactive sulfur. As used herein, the phrase “active sulfur” is defined assulfur containing compounds which would substantially react with machineparts to form metal sulfides at normal engine running temperaturesranging from about 100° C. to below about 400° C. Active sulfur isdistinguished from non-active sulfur, which does not substantially reactat temperatures under 400° C., but which may sufficiently react to formmetal sulfides at temperatures above 400° C. so as to protect engineparts under extreme pressure conditions, or where boundary conditionsexist. One of ordinary skill in the art would readily understand thattemperatures significantly above 400° can occur at various positions inengines that typically operate at lower temperatures, such as below 400°C., due to these boundary regions and extreme pressure regions. Suchboundary regions and extreme pressure regions can occur, for example,when a particular engine part, such as a bearing, is placed under load.Non-active sulfur compounds can be employed that will react to protectengine parts as these higher temperatures, while not substantiallyreacting at the generally lower engine operating temperatures.Accordingly, one of ordinary skill in the art understands that compoundscontaining active sulfur, such as zinc dialkyldithiophosphate (ZDDP),can exert a measurable deleterious effect upon some machines, such asmedium speed diesel engines or machines that contain silver parts, whilenon-active sulfur compounds can still be employed to protect engineparts in these machines. For at least this reason, it may be desirableto omit active sulfur compounds from formulations intended for use insuch machines. One skilled in the art would know how to determine theeffect of sulfur containing compounds on machine parts, such as, forexample, by measuring the amount of silver dissolved in the lubricantand/or the amount of deposits on the silver parts. The term “essentiallyfree” is defined for purposes of this application to be concentrationshaving substantially no measurable deleterious effect.

In some embodiments, the lubricant compositions of the presentapplication are substantially free, such as devoid, of compoundscontaining phosphorus. In other embodiments, the compositions of thepresent application can be substantially free of compounds containingboron. It can be desirable to omit phosphorus and/or boron containingcompounds from formulations of the present application so that theseelements can be used as markers to indicate lubricant contamination. Forexample, railroad engine oils are generally formulated to be free ofphosphorus and boron. While in use, the oils are periodically checkedfor phosphorus and/or boron, the presence of which can indicate that theoil has been contaminated with e.g., ZDDP or, in the case of boron,boron containing coolants, during engine operation. In this manner, thephosphorus and/or boron act as markers to indicate contamination of thelubricant. By the phrase substantially free is meant that thecomposition comprises only trace amounts of phosphorus and/or boron, sothat concentrations of these elements will have substantially no effecton the ability of phosphorus and boron to be used as markers.

Base oils suitable for use in formulating the disclosed compositions canbe selected from any of the synthetic or mineral oils or mixturesthereof. Mineral oils include animal oils and vegetable oils (e.g.,castor oil, lard oil) as well as other mineral lubricating oils such asliquid petroleum oils and solvent treated or acid-treated minerallubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types. Oils derived from coal or shale are alsosuitable. Further, oils derived from a gas-to-liquid process are alsosuitable.

The base oil can be present in a major amount, wherein “major amount” isunderstood to mean greater than or equal to 50%, for example from about80 to about 98 percent by weight of the lubricant composition.

The base oil can have any desired viscosity that is suitable for theintended purpose. Examples of suitable engine oil kinematic viscositiescan range from about 2 to about 150 cSt and, as a further example, fromabout 5 to about 15 cSt at 100° C. Thus, for example, base oils can berated to have viscosity ranges of about SAE 15 to about SAE 250, and asa further example, from about SAE 20W to about SAE 50. Suitableautomotive oils also include multi-grade oils such as 15W-40, 20W-50,75W-140, 80W-90, 85W-140, 85W-90, and the like.

Non-limiting examples of synthetic oils include hydrocarbon oils such aspolymerized and interpolymerized olefins (e.g., polybutylenes,polypropylenes, propylene isobutylene copolymers, etc.);polyalphaolefins such as poly(1-hexenes), poly-(1-octenes),poly(1-decenes), etc. and mixtures thereof; alkylbenzenes (e.g.,dodecylbenzenes, tetradecylbenzenes, di-nonylbenzenes,di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls,terphenyl, alkylated polyphenyls, etc.); alkylated diphenyl ethers andalkylated diphenyl sulfides and the derivatives, analogs and homologsthereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof wherethe terminal hydroxyl moieties have been modified by esterification,etherification, etc., constitute another class of known synthetic oilsthat can be used. Such oils are exemplified by the oils prepared throughpolymerization of ethylene oxide or propylene oxide, the alkyl and arylethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropyleneglycol ether having an average molecular weight of about 1000, diphenylether of polyethylene glycol having a molecular weight of about500-1000, diethyl ether of polypropylene glycol having a molecularweight of about 1000-1500, etc.) or mono- and polycarboxylic estersthereof, for example, the acetic acid esters, mixed C₃₋₈ fatty acidesters, or the C₁₃ Oxo acid diester of tetraethylene glycol.

Another class of synthetic oils that can be used includes the esters ofdicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinicacids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid,sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonicacid, alkyl malonic acids, alkenyl malonic acids, etc.) with a varietyof alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol,2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether,propylene glycol, etc.) Specific examples of these esters includedibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctylsebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate,didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester oflinoleic acid dimer, the complex ester formed by reacting one mole ofsebacic acid with two moles of tetraethylene glycol and two moles of2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include those made from C₅₋₁₂monocarboxylic acids and polyols and polyol ethers such as neopentylglycol, trimethylol propane, pentaerythritol, dipentaerythritol,tripentaerythritol, etc.

Hence, the base oil used which can be used to make the compositions asdescribed herein can be selected from any of the base oils in Groups I-Vas specified in the American Petroleum Institute (API) Base OilInterchangeability Guidelines. Such base oil groups are as follows:

Group I contain less than 90% saturates and/or greater than 0.03% sulfurand have a viscosity index greater than or equal to 80 and less than120; Group II contain greater than or equal to 90% saturates and lessthan or equal to 0.03% sulfur and have a viscosity index greater than orequal to 80 and less than 120; Group III contain greater than or equalto 90% saturates and less than or equal to 0.03% sulfur and have aviscosity index greater than or equal to 120; Group IV arepolyalphaolefins (PAO); and Group V include all other basestocks notincluded in Group I, II, III or IV.

The test methods used in defining the above groups are ASTM D2007 forsaturates; ASTM D2270 for viscosity index; and one of ASTM D2622, 4294,4927 and 3120 for sulfur.

Group IV basestocks, i.e. polyalphaolefins (PAO) include hydrogenatedoligomers of an alpha-olefin, the most important methods ofoligomerisation being free radical processes, Ziegler catalysis, andcationic, Friedel-Crafts catalysis.

The polyalphaolefins typically have viscosities in the range of 2 to 100cSt at 100° C., for example 4 to 8 cSt at 100° C. They can, for example,be oligomers of branched or straight chain alpha-olefins having fromabout 2 to about 30 carbon atoms, non-limiting examples includepolypropenes, polyisobutenes, poly-1-butenes, poly-1-hexenes,poly-1-octenes and poly-1-decene. Included are homopolymers,interpolymers and mixtures.

Regarding the balance of the basestock referred to above, a “Group Ibasestock” also includes a Group I basestock with which basestock(s)from one or more other groups can be admixed, provided that theresulting admixture has characteristics falling within those specifiedabove for Group I basestocks.

Exemplary basestocks include Group I basestocks and mixtures of Group IIbasestocks with Group I bright stock.

Basestocks suitable for use herein can be made using a variety ofdifferent processes including but not limited to distillation, solventrefining, hydrogen processing, oligomerisation, esterification, andre-refining.

The base oil can be an oil derived from Fischer-Tropsch synthesizedhydrocarbons. Fischer-Tropsch synthesized hydrocarbons can be made fromsynthesis gas containing H₂ and CO using a Fischer-Tropsch catalyst.Such hydrocarbons typically require further processing in order to beuseful as the base oil. For example, the hydrocarbons can behydroisomerized using processes disclosed in U.S. Pat. No. 6,103,099 or6,180,575; hydrocracked and hydroisomerized using processes disclosed inU.S. Pat. No. 4,943,672 or 6,096,940; dewaxed using processes disclosedin U.S. Pat. No. 5,882,505; or hydroisomerized and dewaxed usingprocesses disclosed in U.S. Pat. No. 6,013,171; 6,080,301; or 6,165,949.

Unrefined, refined and rerefined oils, either mineral or synthetic (aswell as mixtures of two or more of any of these) of the type disclosedhereinabove can be used in the base oils. Unrefined oils are thoseobtained directly from a mineral or synthetic source without furtherpurification treatment. For example, a shale oil obtained directly fromretorting operations, a petroleum oil obtained directly from primarydistillation or ester oil obtained directly from an esterificationprocess and used without further treatment would be an unrefined oil.Refined oils are similar to the unrefined oils except they have beenfurther treated in one or more purification steps to improve one or moreproperties. Many such purification techniques are known to those skilledin the art such as solvent extraction, secondary distillation, acid orbase extraction, filtration, percolation, etc. Rerefined oils areobtained by processes similar to those used to obtain refined oilsapplied to refined oils which have been already used in service. Suchrerefined oils are also known as reclaimed or reprocessed oils and oftenare additionally processed by techniques directed to removal of spentadditives, contaminants, and oil breakdown products.

According to various embodiments, there is a method of improvingoxidation protection in a lubricant composition. As used herein, theterm “improving oxidation protection” is understood to mean enhancingthe oxidation protection that a composition can provide to a machine,e.g., reducing the amount of infrared carbonyl absorption and/orreducing the kinematic viscosity of a composition used in a machine, ascompared to a composition that is devoid of the combination disclosedherein. The method of improving oxidation can comprise providing to amachine a lubricant composition comprising a major amount of a base oil;and a minor amount of an additive composition comprising (i) a triazolecompound substituted with an aryl moiety, with the proviso that thetriazole compound is not an alkyl bis-3-amino-1,2,4-triazole; and (ii) anitrogen-containing compound represented by the formula (II):

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.

According to various embodiments, there is also disclosed a method oflubricating at least one moving part of a machine, said methodcomprising contacting the at least one moving part with a lubricantcomposition comprising a major amount of a base oil and a minor amountof the disclosed synergistic additive composition.

In other embodiments, there is also disclosed a method for operating amachine comprising adding a lubricant composition comprising a majoramount of a base oil and a minor amount of the disclosed synergisticadditive composition.

The machine in the disclosed methods can be selected from the groupconsisting of spark ignition and compression-ignition internalcombustion engines, including diesel engines, marine engines, rotaryengines, turbine engines, locomotive engines, propulsion engines,aviation piston engines, stationary power generation engines, continuouspower generation engines, and engines comprising silver parts. Moreover,the at least one moving part can be chosen from a gear, piston, bearing,rod, spring, camshaft, crankshaft, rotors, and the like.

The lubricant composition can be any composition that would be effectivein lubricating a machine. In an aspect, the composition is selected fromthe group consisting of medium speed diesel engine oils, passenger carmotor oils, and heavy duty diesel engine oils. In an embodiment, thecomposition is a medium speed diesel engine oil.

EXAMPLES

The following examples are illustrative of the invention and itsadvantageous properties. In these examples as well as elsewhere in thisapplication, all parts and percentages are by weight unless otherwiseindicated. It is intended that these examples are being presented forthe purpose of illustration only and are not intended to limit the scopeof the invention disclosed herein.

Lubricant compositions that were essentially free of compoundscontaining active sulfur, boron and phosphorus were tested for theirability to protect against oxidation. The following examples show thesynergism that exists when a triazole compound and a nitrogen-containingcompound, such as an aryl amine, are formulated into lubricantcomposition, such as an engine oil. The examples also show that thissynergism is unique when compared to antioxidant compounds alone or incombination.

Example 1

In this example, the base lubricant composition was as follows:

TABLE 1 Base Composition COMPONENT Wt. % Functionalized polymer 2-5Dialkyl thiadiazole 0.01-1   Sulfurized olefin (antiwear) 0.01-1   Lowbase detergent 1-4 High base detergent 1-5 Dispersant  1-10 Base oil40/60 blend Balance

As shown in Table 2 below, blends 2 to 8 comprised at least oneadditional component in addition to the above base composition. Atriazole compound was a benzotriazole manufactured by Afton ChemicalCorporation wherein 25 wt. % benzotriazole was dissolved in a primaryt-alkyl amine (Primene JM-T available from Rohm and Haas, Philadelphia,Pa.) and solvent neutral mineral oil so that it would be soluble in thebase composition of Table 1. The aryl amine compound was a dialkyldiphenylamine. In order to rule out the possibility of the primaryt-alkyl amine contributing to the oxidative stability of thecompositions, the primary t-alkyl amine was also tested with thetriazole compound (5), the aryl amine compound (6), and a combination ofthe two (8).

TABLE 2 Lubricant Compositions 1 (Base) 2 3 4 5 6 7 8 N-containing — — —0.30 — 0.30  0.30  0.30 compound (wt. %) Primary t- — — 1.125 — 1.1251.125 — 1.125 alkyl amine (wt. %) Triazole — 0.375 — — 0.375 — 0.3750.375 compound (wt. %)

The oxidation stability of these eight lubricant compositions wasmeasured by the Ethyl Oxidation Test. Oxygen was bubbled through a testtube containing suspended iron, copper and lead coupons and one of thelubricant compositions from Table 2 at 300° F. An air condenser retainedmost of the volatiles, and the lubricant composition was sampled andanalyzed every 24 hours. The used lubricant compositions were evaluatedfor oxidation control by methods well known in the art for measuringkinematic viscosity increase and infrared carbonyl absorptions of theoil oxidation products.

The greater the carbonyl absorption, the less oxidation protection thatparticular lubricant composition imparts to the machine. The greater theincrease in viscosity, the less stable a particular lubricantcomposition is to oxidation. The results are provided in Tables 3 and 4below.

TABLE 3 Viscosity Increase Percent Increase of Lubricant KinematicViscosity at 100° C. Composition 48 Hrs 72 Hrs 96 Hrs Base Blend 4.224.5 56.2 2 5 30.3 71.4 3 7.1 30.5 68.6 4 −5.1 9.2 41.7 5 11.4 37.8 83.36 −1.6 16.8 44.4 7 −1.4 −1.8 −3.9 8 −1.2 −2.7 −4.1

TABLE 4 Infrared Carbonyl Absorption FTIR Carbonyl Absorption Lubricantabs/cm @ 1710 cm⁻¹ Composition 48 Hrs 72 Hrs 96 Hrs Base Blend 108 149178 2 87 119 154 3 94 134 160 4 72 132 166 5 104 154 177 6 78 131 153 7−5 −3 −1 8 7 10 13

As shown in Tables 3 and 4, the base blend comprising the triazolecompound (2), primary t-alkyl amine (3), or nitrogen-containing compound(4) showed some early, small oxidation protection. Thenitrogen-containing compound (4) performed the best out of the threelubricant compositions with a 33% reduction in carbonyl absorption at 48test hours, 11% reduction at 72 hours and a 7% reduction at 96 hours.Viscosity increases for the triazole compound (2) or primary t-alkylamine (3) were comparable to the base blend. The nitrogen-containingcompound (4) showed low viscosity increases at 48 and 72 hours, but alarge viscosity increase at 96 hours. Lubricant composition (6) wascomparable to the nitrogen-containing compound alone (4) in bothcarbonyl absorptions and viscosity increases. Lubricant composition (5)showed virtually no effect on oxidation, with carbonyl absorption equalto the base blend and viscosity increases larger than the base blend.Thus, the triazole compound (2) and primary t-alkyl amine (3) alone orin combination had little effect in oxidation protection of an activesulfur-free base blend as shown by carbonyl absorption or viscosityincreases. With or without the primary t-alkyl amine, thenitrogen-containing compound (4) alone provided some oxidationprotection.

The nitrogen-containing compound in combination with the triazolecompound (7) showed significant synergism by both carbonyl absorptionand viscosity increases. The negative carbonyl absorption values through96 test hours in Table 4 indicate no detectable oxidation taking place.A small amount of oxidation was evidenced by the small viscositydecrease through 96 hours as shown in Table 3. The ternary combinationof nitrogen-containing compound, triazole compound, and primary t-alkylamine (8) showed small amounts of oxidation products by carbonylabsorption and slightly larger viscosity decreases indicating that theprimary t-alkyl amine has a slight pro-oxidation tendency. Thus, thesynergistic effect is attributable to the combination of thenitrogen-containing compound with the triazole compound (7). The primaryt-alkyl amine does not play any role in the observed effect onoxidation.

Example 2

The base composition of Table 1 was again used, but with varying amountsof a triazole compound and a nitrogen-containing compound as shown inTable 5 below.

TABLE 5 Lubricant Compositions 9 10 11 12 13 14 N-containing — — — 0.300.30 0.30 compound (wt. %) Triazole 0.375 0.100 0.050 0.375 0.100 0.050Compound (wt. %)

The oxidation stability of these compositions was also measured by theEthyl Oxidation Test. The compositions were evaluated for oxidationcontrol by methods for measuring kinematic viscosity increase andinfrared carbonyl absorptions of oxidation products as described above.The results are as shown in Tables 6 and 7 below.

TABLE 6 Viscosity Increase Percent Increase of Lubricant KinematicViscosity at 100° C. Composition 48 Hrs 72 Hrs 96 Hrs 9 5 30.3 71.4 108.3 35.7 84.7 11 3.7 27.4 63.4 12 −1.4 −1.8 −3.9 13 −1.8 −8.4 −0.8 14−1.8 −8.7 6.6

TABLE 7 Infrared Carbonyl Absorption FTIR Carbonyl Absorption Lubricantabs/cm @ 1710 cm⁻¹ Composition 48 Hrs 72 Hrs 96 Hrs 9 87 119 154 10 96139 164 11 88 131 145 12 −5 −3 −1 13 6 14 86 14 −8 18 86

The triazole compound in Table 2 was tested at 0.375 wt. %,traditionally a rather high concentration for benzotriazole. As shown inTable 5, the triazole compound alone and with a nitrogen-containingcompound was tested at 0.10 wt. % and 0.05 wt. % benzotriazole todetermine if lower triazole amounts affected the results discussedabove. As shown in Tables 6 and 7, the triazole compound in the baseblend alone used at lower concentrations, e.g., 0.10 wt. % (10) and 0.05wt. % (11), still yielded viscosity increases comparable to the baseblend. The carbonyl absorptions were comparable for all three triazoleconcentrations and only about 20% less than the base blend.

The triazole compound used at the two lower concentration with anitrogen-containing compound, 0.10 wt. % (13) and 0.05 wt. % (14),showed over 90% lower carbonyl absorption at 48 and 72 test hours, and a50% lower carbonyl absorption at 96 hours. The viscosity decreases ofover 8% at 72 hours for both lower concentrations of the triazolecompound showed that some oxidation was occurring. Yet even at 96 testhours, the lowest triazole concentration, 0.05 wt. % (14), showed aviscosity increase of only 6.6%, an 88% decrease over the base blend andan 84% decrease over the nitrogen-containing compound alone in the baseblend (4). Thus, significant oxidation protection as measured bycarbonyl absorption and viscosity change was achieved with anitrogen-containing compound an a triazole compound even at 0.05 wt. %.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the,” include plural referents unlessexpressly and unequivocally limited to one referent. Thus, for example,reference to “an antioxidant” includes two or more differentantioxidants. As used herein, the term “include” and its grammaticalvariants are intended to be non-limiting, such that recitation of itemsin a list is not to the exclusion of other like items that can besubstituted or added to the listed items

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that can vary depending upon thedesired properties sought to be obtained by the present disclosure. Atthe very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or can be presently unforeseen can arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they can be amended are intended to embrace all such alternatives,modifications variations, improvements, and substantial equivalents.

1. A synergistic additive composition comprising: (i) a triazolecompound substituted with an aryl moiety, with the proviso that thetriazole compound is not an alkyl bis-3-amino-1,2,4-triazole; and (ii) anitrogen-containing compound represented by the formula (II):

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido phosphoro, and sulfono.
 2. The synergisticadditive composition of claim 1, wherein R¹ and R² are each an arylmoiety comprising from about 6 to about 30 carbon atoms.
 3. Thesynergistic additive composition of claim 1, wherein the aryl moiety isselected from the group consisting of phenyl, benzyl, naphthyl, andalkaryl.
 4. The synergistic additive composition of claim 3, wherein thealkaryl is selected from the group consisting of alkphenyl andalknaphthyl, wherein the alkyl moiety comprises from about 4 to about 30carbon atoms.
 5. The synergistic additive composition of claim 4,wherein the alkyl moiety of the alkaryl comprises from about 4 to about12 carbon atoms.
 6. The synergistic additive composition of claim 1,wherein the triazole compound is substituted with a substituted orunsubstituted aryl moiety comprising multiple rings.
 7. The synergisticadditive composition of claim 1, wherein the triazole compound issubstituted with a substituted or unsubstituted aryl moiety comprising asingle ring.
 8. The synergistic additive composition of claim 1, whereinthe triazole compound is represented by the formula (I):

wherein R³ is selected from the group consisting of hydrogen and atleast one alkyl moiety comprising from about 1 to about 24 carbon atoms,and wherein R⁴ is selected from the group consisting of hydrogen, atleast one alkyl moiety comprising from about 1 to about 24 carbon atoms,and a substituted hydrocarbyl moiety.
 9. The synergistic additivecomposition of claim 1, wherein the triazole compound is abenzotriazole.
 10. The synergistic additive composition of claim 1,wherein the triazole compound is present in an amount ranging from about0.01 wt. % to about 3 wt. %, relative to the total weight of theadditive composition.
 11. The synergistic additive composition of claim1, wherein the nitrogen-containing compound is present in an amountranging from about 0.07 wt. % to about 33 wt. %, relative to the totalweight of the additive composition.
 12. The synergistic additivecomposition of claim 1, further comprising at least one additiveselected from the group consisting of dispersants, ash-containingdetergents, ashless-detergents, overbased detergents, pour pointdepressing agents, viscosity index improving agents, ash-containingfriction modifier, ashless friction modifier, nitrogen-containingfriction modifier, nitrogen-free friction modifier, esterified frictionmodifier, extreme pressure agents, rust inhibitors, supplementalantioxidants, corrosion inhibitors, anti-foam agents, titaniumcompounds, titanium complexes, organic soluble molybdenum compounds,organic soluble molybdenum complexes, boron-containing compounds,boron-containing complexes, tungsten-containing compounds, andtungsten-containing complexes.
 13. The synergistic additive compositionof claim 1, further comprising at least one molybdenum compound
 14. Thesynergistic additive composition of claim 1, further comprising at leastone titanium compound.
 15. A lubricant composition comprising: a majoramount of a base oil; and a minor amount of a synergistic additivecomposition comprising: (i) a triazole compound substituted with an arylmoiety, with the proviso that the triazole compound is not an alkylbis-3-amino-1,2,4-triazole; and (ii) a nitrogen-containing compoundrepresented by the formula (II):

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.
 16. The lubricantcomposition of claim 15, wherein the lubricant composition isessentially free of compounds containing boron or phosphorus.
 17. Thelubricant composition of claim 15, wherein the lubricant composition isessentially free of zinc dialkyldithiophosphate.
 18. The lubricantcomposition of claim 15, wherein the triazole compound is present in anamount ranging from about 0.05 wt. % to about 0.5 wt. %, relative to thetotal weight of the composition.
 19. The lubricant composition of claim15, wherein the nitrogen-containing compound is present in an amountranging from about 0.01 wt. % to about 10 wt. %, relative to the totalweight of the composition.
 20. The lubricant composition of claim 15,wherein the nitrogen-containing compound is present in an amount rangingfrom about 0.3 wt. % to about 3 wt. %, relative to the total weight ofthe composition.
 21. The lubricant composition of claim 15, wherein thetriazole compound is present at 0.05 wt. % and the nitrogen-containingcompound is present at 0.3 wt. %, relative to the total weight of thecomposition.
 22. The lubricant composition of claim 15, furthercomprising at least one additive selected from the group consisting ofdispersants, ash-containing detergents, ashless-detergents, overbaseddetergents, pour point depressing agents, viscosity index improvingagents, ash-containing friction modifier, ashless friction modifier,nitrogen-containing friction modifier, nitrogen-free friction modifier,esterified friction modifier, extreme pressure agents, rust inhibitors,supplemental antioxidants, corrosion inhibitors, anti-foam agents,titanium compounds, titanium complexes, organic soluble molybdenumcompounds, organic soluble molybdenum complexes, boron-containingcompounds, boron-containing complexes, tungsten-containing compounds,and tungsten-containing complexes.
 23. The lubricant composition ofclaim 15, wherein the lubricant composition is selected from the groupconsisting of medium speed diesel engine oils, passenger car motor oils,and heavy duty diesel engine oils.
 24. The lubricant composition ofclaim 15, further comprising at least one molybdenum compound
 25. Thelubricant composition of claim 15, further comprising at least onetitanium compound.
 26. A lubricant composition comprising: a majoramount of a base oil; and a minor amount of an additive compositioncomprising: (i) a triazole compound substituted with an aryl moiety,with the proviso that the triazole compound is not an alkylbis-3-amino-1,2,4-triazole; and (ii) a nitrogen-containing compoundrepresented by the formula (II):

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.
 27. A method ofimproving oxidation protection of a lubricant composition, said methodcomprising: providing to a machine a lubricant composition comprising amajor amount of a base oil; and a minor amount of an additivecomposition comprising: (i) a triazole compound substituted with an arylmoiety, with the proviso that the triazole compound is not an alkylbis-3-amino-1,2,4-triazole; and (ii) a nitrogen-containing compoundrepresented by the formula (II):

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.
 28. The method ofclaim 27, wherein the machine is selected from the group consisting ofspark ignition and compression-ignition internal combustion engines. 29.The method of claim 28, wherein the engine is selected from the groupconsisting of diesel engines, marine engines, rotary engines, turbineengines, locomotive engines, propulsion engines, aviation pistonengines, stationary power generation engines, continuous powergeneration engines, and engines comprising silver parts.
 30. A methodfor operating a machine comprising: adding to the machine a lubricatingcomposition comprising a major amount of a base oil; and a minor amountof an additive composition comprising: (i) a triazole compoundsubstituted with an aryl moiety, with the proviso that the triazolecompound is not an alkyl bis-3-amino-1,2,4-triazole; and (ii) anitrogen-containing compound represented by the formula (II):

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.
 31. The method ofclaim 30, wherein the machine is selected from the group consisting ofspark ignition and compression-ignition internal combustion engines. 32.The method of claim 31, wherein the engine is selected from the groupconsisting of diesel engines, marine engines, rotary engines, turbineengines, locomotive engines, propulsion engines, aviation pistonengines, stationary power generation engines, continuous powergeneration engines, and engines comprising silver parts.
 33. A method oflubricating at least one moving part of a machine, said methodcomprising: contacting the at least one moving part with a lubricantcomposition comprising a major amount of a base oil; and a minor amountof a synergistic additive composition comprising: (i) a triazolecompound substituted with an aryl moiety, with the proviso that thetriazole compound is not an alkyl bis-3-amino-1,2,4-triazole; and (ii) anitrogen-containing compound represented by the formula (II):

wherein R¹ and R² are each independently selected from the groupconsisting of at least one aryl moiety comprising from about 6 to about30 carbon atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substitutedhydrocarbyl, amino, amido, phosphoro, and sulfono.
 34. The method ofclaim 33, wherein the machine is selected from the group consisting ofspark ignition and compression-ignition internal combustion engines 35.The method of claim 34, wherein the at least one moving part is selectedfrom the group consisting of gears, pistons, bearings, rods, springs,camshafts, crankshafts, and rotors.